Network : Network > Interfaces

Layer 2 Bridged Mode
SonicOS includes L2 (Layer 2) Bridged Mode, a method of unobtrusively integrating a firewall into any Ethernet network. L2 Bridged Mode is ostensibly similar to SonicOS’s Transparent Mode in that it enables a firewall to share a common subnet across two interfaces, and to perform stateful and deep-packet inspection on all traversing IP traffic, but it is functionally more versatile.
In particular, L2 Bridged Mode employs a secure learning bridge architecture, enabling it to pass and inspect traffic types that cannot be handled by many other methods of transparent security appliance integration. Using L2 Bridged Mode, a Dell SonicWALL Security Appliance can be non-disruptively added to any Ethernet network to provide in-line deep-packet inspection for all traversing IPv4 TCP and UDP traffic. In this scenario, the firewall is not used for security enforcement, but instead for bidirectional scanning, blocking viruses and spyware, and stopping intrusion attempts.
Unlike other transparent solutions, L2 Bridged Mode can pass all traffic types, including IEEE 802.1Q VLANs, Spanning Tree Protocol, multicast, broadcast, and IPv6, ensuring that all network communications will continue uninterrupted.
Another aspect of the versatility of L2 Bridged Mode is that you can use it to configure IPS Sniffer Mode. Supported on Dell SonicWALL Security Appliances, IPS Sniffer Mode uses a single interface of a Bridge-Pair to monitor network traffic from a mirrored port on a switch. IPS Sniffer Mode provides intrusion detection, but cannot block malicious traffic because the firewall is not connected inline with the traffic flow. For more information about IPS Sniffer Mode, see IPS Sniffer Mode .
L2 Bridged Mode provides an ideal solution for networks that already have an existing firewall, and do not have immediate plans to replace their existing firewall but wish to add the security of SonicWALL Unified Threat Management (UTM) deep-packet inspection, such as Intrusion Prevention Services, Gateway Anti Virus, and Gateway Anti Spyware. If you do not have SonicWALL UTM security services subscriptions, you may sign up for free trials from the Security Service > Summary page of your SonicWALL.
You can also use L2 Bridged Mode in a High Availability deployment. This scenario is explained in the Layer 2 Bridged Mode with High Availability .
Key Features of SonicOS Layer 2 Bridged Mode
The following table outlines the benefits of each key feature of layer 2 bridged mode:
Key Concepts to Configuring L2 Bridged Mode and Transparent Mode
The following terms will be used when referring to the operation and configuration of L2 Bridged Mode:
L2 Bridged Mode – A method of configuring a Dell SonicWALL Security Appliance, which enables the firewall to be inserted inline into an existing network with absolute transparency, beyond even that provided by Transparent Mode. Layer 2 Bridged Mode also refers to the IP Assignment configuration that is selected for Secondary Bridge Interfaces that are placed into a Bridge-Pair.
Transparent Mode – A method of configuring a Dell SonicWALL Security Appliance that allows the firewall to be inserted into an existing network without the need for IP reconfiguration by spanning a single IP subnet across two or more interfaces through the use of automatically applied ARP and routing logic.
IP Assignment – When configuring a Trusted (LAN) or Public (DMZ) interface, the IP Assignment for the interface can either be:
Static – The IP address for the interface is manually entered.
Transparent Mode – The IP address(es) for the interface is assigned using an Address Object (Host, Range, or Group) that falls within the WAN Primary IP subnet, effectively spanning the subnet from the WAN interface to the assigned interface.
Layer 2 Bridged Mode – An interface placed in this mode becomes the Secondary Bridge Interface to the Primary Bridge Interface to which it is paired. The resulting Bridge-Pair will then behave like a two-port learning bridge with full L2 transparency, and all IP traffic that passes through will be subjected to full stateful failover and deep packet inspection.
Bridge-Pair – The logical interface set composed of a Primary Bridge Interface and a Secondary Bridge Interface. The terms primary and secondary do not imply any inherent level of operational dominance or subordination; both interfaces continue to be treated according to their zone type, and to pass IP traffic according to their configured Access Rules. Non-IPv4 traffic across the Bridge-Pair is controlled by the Block all non-IPv4 traffic setting on the Secondary Bridge Interface. A system may support as many Bridge Pairs as it has interface pairs available. In other words, the maximum number of Bridge-Pairs is equal to ½ the number of physical interfaces on the platform. Membership in a Bridge-Pair does not preclude an interface from conventional behavior; for example, if X1 is configured as a Primary Bridge Interface paired to X3 as a Secondary Bridge Interface, X1 can simultaneously operate in its traditional role as the Primary WAN, performing NAT for Internet-bound traffic through the Auto-added X1 Default NAT Policy.
Primary Bridge Interface – A designation that is assigned to an interface once a Secondary Bridge Interface has been paired to it. A Primary Bridge Interface can belong to an Untrusted (WAN), Trusted (LAN), or Public (DMZ) zone.
Secondary Bridge Interface – A designation that is assigned to an interface whose IP Assignment has been configured for Layer 2 Bridged Mode. A Secondary Bridge Interface can belong to a Trusted (LAN), or Public (DMZ) zone.
Bridge Management Address – The address of the Primary Bridge Interface is shared by both interfaces of the Bridge-Pair. If the Primary Bridge Interface also happens to be the Primary WAN interface, it is this address that is uses for outbound communications by the firewall, such as NTP, and License Manager updates. Hosts that are connected to either segment of the Bridge-Pair may also use the Bridge Management Address as their gateway, as will be common in Mixed-Mode deployments.
Bridge-Partner – The term used to refer to the other member of a Bridge-Pair.
Non-IPv4 Traffic - SonicOS supports the following IP protocol types: ICMP (1), IGMP (2), TCP (6), UDP (17), GRE (47), ESP (50), AH (51), EIGRP (88), OSPF (89), PIM-SM (103), L2TP (115). More esoteric IP types, such as Combat Radio Transport Protocol (126), are not natively handled by the firewall, nor are non-IPv4 traffic types such as IPX or (currently) IPv6. L2 Bridged Mode can be configured to either pass or drop Non-IPv4 traffic.
Captive-Bridged Mode – This optional mode of L2 Bridge operation prevents traffic that has entered an L2 bridge from being forwarded to a non-Bridge-Pair interface. By default, L2 Bridge logic will forward traffic that has entered the L2 Bridge to its destination along the most optimal path as determined by ARP and routing tables. In some cases, the most optimal path might involve routing or NATing to a non-Bridge-Pair interface. Activating Captive-Bridged Mode ensures that traffic which enters an L2 Bridge exits the L2 Bridge rather than taking its most logically optimal path. In general, this mode of operation is only required in complex networks with redundant paths, where strict path adherence is required.
Pure L2 Bridge Topology – Refers to deployments where the firewall will be used strictly in L2 Bridged Mode for the purposes of providing in-line security to a network. This means that all traffic entering one side of the Bridge-Pair will be bound for the other side, and will not be routed/NATed through a different interface. This will be common in cases where there is an existing perimeter security appliance, or where in-line security is desired along some path (for example, inter-departmentally, or on a trunked link between two switches) of an existing network. Pure L2 Bridge Topology is not a functional limitation, but rather a topological description of a common deployment in heterogeneous environments.
Mixed-Mode Topology – Refers to deployments where the Bridge-Pair will not will not be the only point of ingress/egress through the firewall. This means that traffic entering one side of the Bridge-Pair may be destined to be routed/NATed through a different interface. This will be common when the firewall is simultaneously used to provide security to one or more Bridge-Pair while also providing:
Comparing L2 Bridged Mode to Transparent Mode
While Transparent Mode allows a security appliance running SonicOS to be introduced into an existing network without the need for re-addressing, it presents a certain level of disruptiveness, particularly with regard to ARP, VLAN support, multiple subnets, and non-IPv4 traffic types. Consider a scenario where a Transparent Mode SonicWALL appliance has just been added to the network with a goal of minimally disruptive integration, particularly:
ARP in Transparent Mode
ARP – Address Resolution Protocol (the mechanism by which unique hardware addresses on network interface cards are associated to IP addresses) is proxied in Transparent Mode. If the Workstation on Server on the left had previously resolved the Router ( to its MAC address 00:99:10:10:10:10, this cached ARP entry would have to be cleared before these hosts could communicate through the firewall. This is because the firewall proxies (or answers on behalf of) the gateway’s IP ( for hosts connected to interfaces operating in Transparent Mode. So when the Workstation at the left attempts to resolve, the ARP request it sends is responded to by the firewall with its own X0 MAC address (00:06:B1:10:10:10).
The firewall also proxy ARPs the IP addresses specified in the Transparent Range ( to assigned to an interface in Transparent Mode for ARP requests received on the X1 (Primary WAN) interface. If the Router had previously resolved the Server ( to its MAC address 00:AA:BB:CC:DD:EE, this cached ARP entry would have to be cleared before the router could communicate with the host through the firewall. This typically requires a flushing of the router’s ARP cache either from its management interface or through a reboot. Once the router’s ARP cache is cleared, it can then send a new ARP request for, to which the firewall will respond with its X1 MAC 00:06:B1:10:10:11.
VLAN Support in Transparent Mode
While the network depicted in the above diagram is simple, it is not uncommon for larger networks to use VLANs for segmentation of traffic. If this was such a network, where the link between the switch and the router was a VLAN trunk, a Transparent Mode SonicWALL would have been able to terminate the VLANs to subinterfaces on either side of the link, but it would have required unique addressing; that is, non-Transparent Mode operation requiring re-addressing on at least one side. This is because only the Primary WAN interface can be used as the source for Transparent Mode address space.
Multiple Subnets in Transparent Mode
It is also common for larger networks to employ multiple subnets, be they on a single wire, on separate VLANs, multiple wires, or some combination. While Transparent Mode is capable of supporting multiple subnets through the use of Static ARP and Route entries, as the Technote describes, it is not an effortless process.
Non-IPv4 Traffic in Transparent Mode
Transparent Mode will drop (and generally log) all non-IPv4 traffic, precluding it from passing other traffic types, such as IPX, or unhandled IP types.
L2 Bridged Mode addresses these common Transparent Mode deployment issues and is described in the following section.
ARP in L2 Bridged Mode
L2 Bridged Mode employs a learning bridge design where it will dynamically determine which hosts are on which interface of an L2 Bridge (referred to as a Bridge-Pair). ARP is passed through natively, meaning that a host communicating across an L2 Bridge will see the actual host MAC addresses of their peers. For example, the Workstation communicating with the Router ( will see the router as 00:99:10:10:10:10, and the Router will see the Workstation ( as 00:AA:BB:CC:DD:EE.
This behavior allows for a SonicWALL operating in L2 Bridged Mode to be introduced into an existing network with no disruption to most network communications other than that caused by the momentary discontinuity of the physical insertion.
Please note that stream-based TCP protocols communications (for example, an FTP session between a client and a server) will need to be re-established upon the insertion of an L2 Bridged Mode firewall. This is by design so as to maintain the security afforded by stateful packet inspection; since the stateful packet inspection engine can not have knowledge of the TCP connections which pre-existed it, it will drop these established packets with a log event such as TCP packet received on non-existent/closed connection; TCP packet dropped.
VLAN Support in L2 Bridged Mode
On Dell SonicWALL Security Appliances, L2 Bridged Mode provides fine control over 802.1Q VLAN traffic traversing an L2 Bridge. The default handling of VLANs is to allow and preserve all 802.1Q VLAN tags as they pass through an L2 Bridge, while still applying all firewall rules, and stateful and deep-packet inspection to the encapsulated traffic. It is further possible to specify white/black lists for allowed/disallowed VLAN IDs through the L2 Bridge.
This allows a SonicWALL operating in L2 Bridged Mode to be inserted, for example, inline into a VLAN trunk carrying any number of VLANs, and to provide full security services to all IPv4 traffic traversing the VLAN without the need for explicit configuration of any of the VLAN IDs or subnets. Firewall Access Rules can also, optionally, be applied to all VLAN traffic passing through the L2 Bridged Mode because of the method of handling VLAN traffic.
L2 Bridge IP Packet Path
Figure 8. L2 Bridge IP packet flow
The following sequence of events describes the above flow diagram:
In general, the destination for packets entering an L2 Bridge will be the Bridge-Partner interface (that is, the other side of the bridge). In these cases, no translation will be performed.
In cases where the L2 Bridge Management Address is the gateway, as will sometimes be the case in Mixed-Mode topologies, then NAT will be applied as need (see the L2 Bridge Path Determination section for more details).
It is possible to construct a Firewall Access Rule to control any IP packet, independent of its VLAN membership, by any of its IP elements, such as source IP, destination IP, or service type. If the packet is disallowed, it will be dropped and logged. If the packet is allowed, it will continue.
Multiple Subnets in L2 Bridged Mode
L2 Bridged Mode is capable of handling any number of subnets across the bridge, as described above. The default behavior is to allow all subnets, but Access Rules can be applied to control traffic as needed.
Non-IPv4 Traffic in L2 Bridged Mode
Unsupported traffic will, by default, be passed from one L2 Bridge interface to the Bridge-Partner interface. This allows the firewall to pass other traffic types, including LLC packets such as Spanning Tree, other EtherTypes, such as MPLS label switched packets (EtherType 0x8847), Appletalk (EtherType 0x809b), and the ever-popular Banyan Vines (EtherType 0xbad). These non-IPv4 packets will only be passed across the Bridge, they will not be inspected or controlled by the packet handler. If these traffic types are not needed or desired, the bridging behavior can be changed by enabling the Block all non-IPv4 traffic option on the Secondary Bridge Interface configuration page.
Comparison of L2 Bridged Mode to Transparent Mode
Benefits of Transparent Mode over L2 Bridged Mode
Two interfaces are the maximum allowed in an L2 Bridge Pair. If more than two interfaces are required to operate on the same subnet, Transparent Mode should be considered.
L2 Bridge Path Determination
Packets received by the firewall on Bridge-Pair interfaces must be forwarded along to the appropriate and optimal path toward their destination, whether that path is the Bridge-Partner, some other physical or sub interface, or a VPN tunnel. Similarly, packets arriving from other paths (physical, virtual or VPN) bound for a host on a Bridge-Pair must be sent out over the correct Bridge-Pair interface. The following summary describes, in order, the logic that is applied to path determinations for these cases:
If present, the most specific non-default route to the destination is chosen. This would cover, for example:
In this last case, since the destination is unknown until after an ARP response is received, the destination zone also remains unknown until that time. This precludes the firewall from being able to apply the appropriate Access Rule until after path determination is completed. Upon completion, the correct Access Rule will be applied to subsequent related traffic.
With regard to address translation (NAT) of traffic arriving on an L2 Bridge-Pair interface:
If the path is determined to be via the WAN, then the default Auto-added [interface] outbound NAT Policy for X1 WAN will apply, and the packet’s source will be translated for delivery to the Internet. This is common in the case of Mixed-Mode topologies as described in Internal Security .
L2 Bridge Interface Zone Selection
Bridge-Pair interface zone assignment should be done according to your network’s traffic flow requirements. Unlike Transparent Mode, which imposes a system of “more trusted to less trusted” by requiring that the source interface be the Primary WAN, and the transparent interface be Trusted or Public, L2 Bridged Mode allows for greater control of operational levels of trust. Specifically, L2 Bridged Mode allows for the Primary and Secondary Bridge Interfaces to be assigned to the same or different zones (for example, LAN+LAN, LAN+DMZ, WAN+CustomLAN, etc.) This will affect not only the default Access Rules that are applied to the traffic, but also the manner in which Deep Packet Inspection security services are applied to the traffic traversing the bridge. Important areas to consider when choosing and configuring interfaces to use in a Bridge-Pair are Security Services, Access Rules, and WAN connectivity:
Security Services Directionality
As it will be one of the primary employments of L2 Bridged Mode, understanding the application of security services is important to the proper zone selection for Bridge-Pair interfaces. Security services applicability is based on the following criteria:
The direction of the traffic. The direction of the traffic as it pertains to IPS is primarily determined by the Source and Destination zone of the traffic flow. When a packet is received by the firewall, its source zone is generally immediately known, and its destination zone is quickly determined by doing a route (or VPN) lookup.
Based on the source and destination, the packet’s directionality is categorized as either Incoming or Outgoing, (not to be confused with Inbound and Outbound) where the following criteria is used to make the determination:
In addition to this categorization, packets traveling to/from zones with levels of additional trust, which are inherently afforded heightened levels of security (LAN|Wireless|Encrypted<-->LAN|Wireless|Encrypted) are given the special Trust classification. Traffic with the Trust classification has all signatures applied (Incoming, Outgoing, and Bidirectional).
The direction of the signature. This pertains primarily to IPS, where each signature is assigned a direction by SonicWALL’s signature development team. This is done as an optimization to minimize false positives. Signature directions are:
Incoming – Applies to Incoming and Trust. The majority of signatures are Incoming, and they include all forms of application exploits and all enumeration and footprinting attempts. Approximately 85% of signatures are Incoming.
Outgoing – Applies to Outgoing and Trust. Examples of Outgoing signatures would include IM and P2P login attempts, and responses to successfully launched exploits (for example, Attack Responses). Approximately 10% of signatures are Outgoing.
Bidirectional – Applies to all. Examples of Bidirectional signatures would include IM file transfers, various NetBIOS attacks (for example, Sasser communications) and a variety of DoS attacks (for example, UDP/TCP traffic destined to port 0). Approximately 5% of signatures are Bidirectional.
Zone application. For a signature to be triggered, the desired security service must be active on at least one of the zones it traverses. For example, a host on the Internet (X1, WAN) accessing a Microsoft Terminal Server (on X3, Secondary Bridge Interface, LAN) will trigger the Incoming signature “IPS Detection Alert: MISC MS Terminal server request, SID: 436, Priority: Low” if IPS is active on the WAN, the LAN, or both.
Access Rule Defaults
Default, zone-to-zone Access Rules. The default Access Rules should be considered, although they can be modified as needed. The defaults are as follows:
Figure 9. Access rule defaults
WAN Connectivity
Internet (WAN) connectivity is required for stack communications, such as licensing, security services signature downloads, NTP (time synchronization), and CFS (Content Filtering Services). At present, these communications can only occur through the Primary WAN interface. If you require these types of communication, the Primary WAN should have a path to the Internet. Whether or not the Primary WAN is employed as part of a Bridge-Pair will not affect its ability to provide these stack communications.
Sample Topologies
The following are sample topologies depicting common deployments. Inline Layer 2 Bridged Mode represents the addition of a Dell SonicWALL Security Appliance to provide security services in a network where an existing firewall is in place. Perimeter Security represents the addition of a Dell SonicWALL Security Appliance in pure L2 Bridged Mode to an existing network, where the firewall is placed near the perimeter of the network. Internal Security represents the full integration of a Dell SonicWALL Security Appliance in mixed-mode, where it provides simultaneous L2 bridging, WLAN services, and NATed WAN access. Layer 2 Bridged Mode with High Availability represents the mixed-mode scenario where the firewall HA pair provide high availability along with L2 bridging. Layer 2 Bridged Mode with SSL VPN represents the scenario where a SonicWALL Aventail SSL VPN or SonicWALL SSL VPN Series appliance is deployed in conjunction with L2 Bridged Mode.
Wireless Layer 2 Bridge
In wireless mode, after bridging the wireless (WLAN) interface to a LAN or DMZ zone, the WLAN zone becomes the secondary bridged interface, allowing wireless clients to share the same subnet and DHCP pool as their wired counterparts.
To configure a WLAN to LAN Layer 2 interface bridge:
Navigate to the Network > Interfaces page in the SonicOS management interface.
Click the Configure icon for the wireless interface you wish to bridge. The Edit Interface window displays.
Select Layer 2 Bridged Mode as the Mode / IP Assignment from the drop-down men.
Select the Interface to which the WLAN should be bridged from the Bridged To drop-down menu. In this instance, the X0 (default LAN zone) is chosen.
Inline Layer 2 Bridged Mode
This method is useful in networks where there is an existing firewall that will remain in place, but you wish to utilize the firewall’s security services without making major changes to the network. By placing the firewall in Layer 2 Bridged Mode, the X0 and X1 interfaces become part of the same broadcast domain/network (that of the X1 WAN interface).
This example refers to a Dell SonicWALL Security Appliance installed in a Hewlett Packard ProCurve switching environment. SonicWALL is a member of HP’s ProCurve Alliance – more details can be found at the following location:
HP’s ProCurve Manager Plus (PCM+) and HP Network Immunity Manager (NIM) server software packages can be used to manage the switches as well as some aspects of the Dell SonicWALL Security Appliance.
To configure the firewall for this scenario, navigate to the Network > Interfaces page and click on the configure icon for the X0 LAN interface. On the X0 Settings page, set the IP Assignment to ‘Layer 2 Bridged Mode’ and set the Bridged To: interface to ‘X1’. Also make sure that the interface is configured for HTTP and SNMP so it can be managed from the DMZ by PCM+/NIM. Click OK to save and activate the change.
You will also need to make sure to modify the firewall access rules to allow traffic from the LAN to WAN, and from the WAN to the LAN, otherwise traffic will not pass successfully. You may also need to modify routing information on your firewall if your PCM+/NIM server is placed on the DMZ.
Perimeter Security
Perimeter Security is a network scenario where the firewall is added to the perimeter for the purpose of providing security services (the network may or may not have an existing firewall between the firewall and the router). In this scenario, everything below the firewall (the Primary Bridge Interface segment) will generally be considered as having a lower level of trust than everything to the left of the firewall (the Secondary Bridge Interface segment). For that reason, it would be appropriate to use X1 (Primary WAN) as the Primary Bridge Interface.
Traffic from hosts connected to the Secondary Bridge Interface (LAN) would be permitted outbound through the firewall to their gateways (VLAN interfaces on the L3 switch and then through the router), while traffic from the Primary Bridge Interface (WAN) would, by default, not be permitted inbound.
If there were public servers, for example, a mail and Web server, on the Secondary Bridge Interface (LAN) segment, an Access Rule allowing WAN->LAN traffic for the appropriate IP addresses and services could be added to allow inbound traffic to those servers.
Internal Security
A network scenario where the firewall will act as the perimeter security device and secure wireless platform. Simultaneously, it will provide L2 Bridge security between the workstation and server segments of the network without having to readdress any of the workstation or servers.
This typical inter-departmental Mixed Mode topology deployment demonstrates how the firewall can simultaneously Bridge and route/NAT. Traffic to/from the Primary Bridge Interface (Server) segment from/to the Secondary Bridge Interface (Workstation) segment will pass through the L2 Bridge.
Since both interfaces of the Bridge-Pair are assigned to a Trusted (LAN) zone, the following will apply:
Consider, for the point of contrast, what would occur if the X2 (Primary Bridge Interface) was instead assigned to a Public (DMZ) zone: All the Workstations would be able to reach the Servers, but the Servers would not be able to initiate communications to the Workstations. While this would probably support the traffic flow requirements (i.e. Workstations initiating sessions to Servers), it would have two undesirable effects:
Security services directionality would be classified as Outgoing for traffic from the Workstations to the Server since the traffic would have a Trusted source zone and a Public destination zone. This might be sub-optimal since it would provide less scrutiny than the Incoming or (ideally) Trust classifications.
Security services directionality would be classified as Trust, and all signatures (Incoming, Outgoing, and Bidirectional) will be applied, providing the highest level of security to/from both segments.
For detailed instructions on configuring interfaces in Layer 2 Bridged Mode, see Configuring Layer 2 Bridged Mode
Layer 2 Bridged Mode with High Availability
This method is appropriate in networks where both High Availability and Layer 2 Bridged Mode are desired. This example is for Dell SonicWALL Security Appliances, and assumes the use of switches with VLANs configured.
Figure 10. Internal security: Example where both High Availability and Layer 2 Bridged Mode are desired
The firewall HA pair consists of two firewalls, connected together on port X5, the designated HA port. Port X1 on each appliance is configured for normal WAN connectivity and is used for access to the management interface of that device. Layer 2 Bridged Mode is implemented with port X0 bridged to port X2.
When setting up this scenario, there are several things to take note of on both the firewalls and the switches.
On the firewalls:
On the switches:
Layer 2 Bridged Mode with SSL VPN
This sample topology covers the proper installation of a SonicWALL network security appliance into your existing SonicWALL EX-Series SSL VPN or SonicWALL SSL VPN networking environment. By placing the appliance into Layer 2 Bridged Mode, with an internal, private connection to the SSL VPN appliance, you can scan for viruses, spyware, and intrusions in both directions. In this scenario the firewall is not used for security enforcement, but instead for bidirectional scanning, blocking viruses and spyware, and stopping intrusion attempts. When programmed correctly, the network security appliance will not interrupt network traffic, unless the behavior or content of the traffic is determined to be undesirable. Both one- and two-port deployments of the Dell SonicWALL Security Appliance are covered in this section.
WAN to LAN Access Rules
Because the network security appliance will be used in this deployment scenario only as an enforcement point for anti-virus, anti-spyware and intrusion prevention, its existing security policy must be modified to allow traffic to pass in both directions between the WAN and LAN.
On the Firewall > Access Rules page, click the Configure icon for the intersection of WAN to LAN traffic. Click the Configure icon next to the default rule that implicitly blocks uninitiated traffic from the WAN to the LAN. In the Edit Rule window, select Allow for the Action setting, and then click OK.
Configure the Network Interfaces and Activate L2B Mode
In this scenario the WAN interface is used for the following:
The LAN interface on the network security appliance is used to monitor the unencrypted client traffic coming from the external interface of the SSL VPN appliance. This is the reason for running in Layer 2 Bridged Mode (instead of reconfiguring the external interface of the SSL VPN appliance to see the LAN interface as the default route).
On the Network > Interfaces page of the SonicOS management interface, click the Configure icon for the WAN interface, and then assign it an address that can access the Internet so that the appliance can obtain signature updates and communicate with NTP.
The gateway and internal/external DNS address settings will match those of your SSL VPN appliance:
IP address: This must match the address for the internal interface on the SSL VPN appliance.
Subnet Mask, Default Gateway, and DNS Server(s): Make these addresses match your SSL VPN appliance settings.
For the Management setting, select the HTTPS and Ping check boxes. Click OK to save and activate the changes.
To configure the LAN interface settings, navigate to the Network > Interfaces page and click the Configure icon for the LAN interface.
For the IP Assignment setting, select Layer 2 Bridged Mode. For the Bridged to setting, select X1.
If you also need to pass VLAN tagged traffic, supported on firewalls, click the VLAN Filtering tab and add all of the VLANs that will need to be passed.
Click OK to save and activate the change. You may be automatically disconnected from the network security appliance’s management interface. You can now disconnect your management laptop or desktop from the appliance’s X0 interface and power the appliance off before physically connecting it to your network.
Install the Dell SonicWALL Security Appliance between the network and SSL VPN appliance
Regardless of your deployment method (single- or dual-homed), the firewall should be placed between the X0/LAN interface of the SSL VPN appliance and the connection to your internal network. This allows the device to connect out to SonicWALL’s licensing and signature update servers, and to scan the decrypted traffic from external clients requesting access to internal network resources.
If your SSL VPN appliance is in two-port mode behind a third-party firewall, it is dual-homed.
To connect a dual-homed SSL VPN appliance, follow these steps:
If your SSL VPN appliance is in one-port mode in the DMZ of a third-party firewall, it is single-homed.
To connect a single-homed SSL VPN appliance, follow these steps:
Configure or Verify Settings
From a management station inside your network, you should now be able to access the management interface on the network security appliance using its WAN IP address.
Make sure that all security services for the Dell SonicWALL Security Appliance are enabled. See Licensing Services and Activating Security Services on Each Zone .
SonicWALL Content Filtering Service must be disabled before the device is deployed in conjunction with a SonicWALL Aventail SSL VPN appliance. On the Network > Zones page, click Configure next to the LAN (X0) zone, clear the Enforce Content Filtering Service check box and then click OK.
If you have not yet changed the administrative password on the Dell SonicWALL Security Appliance, you can do so on the System > Administration page.
To test access to your network from an external client, connect to the SSL VPN appliance and log in. Once connected, attempt to access to your internal network resources. If there are any problems, review your configuration and see Configuring the Common Settings for L2 Bridged Mode Deployments .